Gap-sealing device

ABSTRACT

A gap-sealing device suitable for filling and sealing gaps in the joints of pavements on bridges, overpasses, ramps, parking structures, and the like and joints in multilayered structures comprises a pair of parallel, reinforced, elastomeric anchor members respectively secured to the facing ends of the adjacent concrete pavement slabs forming the joint, and a sealing element removably held at its longitudinal edges in said anchor members and extending transversely of the pavement in the gaps between said members.

Bowman et al.

[ Nov. 26, 1974 I [54] GAP-SEALING DEVICE 3,598,026 8/1971 Johnson ..L 404/74 68 l 1973 M D ll 404 67 [75] lnvemofsl Thmas c-BowmaniBuffaloi 372,379 341973 Kcfest xi 404168 Stewart C. Watson, Williamsville, Y a both of NY. FOREIGN PATENTS OR APPLICATIONS AssigneeZ watsolbnowman Associates, Inc, 410,034 l0/l966 Switzerland 404/67 Buffalo N.Y 475,428 8/1969 Switzerland 404/67 [22] Filed: June 1972 Primary Examiner-Nile C. Byers, Jr. [21] L 259,513 Attorney, Agent, or Firm-Ashan F. Harlan, Jr.

[52] U5. Cl. 404/69 ABSTRACT [51] Int. Cl. E0lc 11/02 A gap sealing device Suitable for filling and sealing [58] Field of Search 404/64, 65, 66, 67, 68, gaps in the joints of pavements on bridges own-passes, 404/69, 47 ramps, parkingstructures, and the like and joints in a a multilayered structures comprises a pair of parallel, [56] References C'ted reinforced, elastomeric anchor members respectively UNITED STATES PATENTS secured to the facing ends of the adjacent concrete 2.246903 6/l94l Spears 404/48 Pavement Slabs forming the joint, and a Sealing 2,354,485 7/!944 Slaughter 248/74 PB ment removably held at its longitudinal edges in said 2,619.884 l2/I952 Jacobson 404/65 anchor members and extending transversely of the 3,218,94l ll/l965 Daum 404/65 pavement in the gaps between said members. 3,375,763 4/l968 Welch 404/67 X 3,570,378 3ll97l Honegger 404/69 16 Claims, 11 Drawing Figures 9 a 75 79 39 77 73 4 a 76 76 Q 39 Vi J 25] 5 7943 4 25 r 1L N as w I we. 7, 75 9 0 Q o o f \4, ez' 7:? 39 V k e:f, :er\ -& V

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PATENTEL, NUV 2 6 I974 sum 2 or a GAP-SEALING DEVICE BACKGROUND OF THE INVENTION This invention is concerned with gap-saling devices and relates in particular to such devices as are employed in filling and sealing gaps in the joints of pavements on bridges, overpasses, ramps, and the like.

Gaps in the joints of the pavements onbridges and the like are provided to permit relative movement of the structural sections on either side. Such relative movement may occur as a result of expansion and contraction, usually caused by changes in temperature, and also as a result of deflections in the structure and shifting of bearings and/or foundations. Although in some installations these gaps are left open or partially closed by relatively moving elements, it is often desirable to seal them to prevent entrance of dirt and other debris and to prevent passage of water therethrough. The means employed for sealing the gaps must provide sealing during widely varying weather conditions and during considerable relative movement of the abutting structural sections, while being essentially unaffected by trafiic over the gap and not interfering with such traffic. With many of the devices provided in the prior art for use in sealing pavement joints the sealing means is subjected to excessive stresses and/or wear resulting in failure, and/or the devices are difficult to install or to repair.

SUMMARY OF THE INVENTION By the present invention there is provided agapsealing device suitable for filling and sealing gaps in the joints of pavements on bridges, overpasses, ramps and the like which solves problems encountered with prior devices designed for this purpose. The novel device of the present invention is readily and quickly installed and, if necessary, can be readily repaired. Moreover, it is very durable because it is quite wear-resistant and is subjected to only very small working stresses. It completely eliminates the transmission of deleterious stresses to the structure. It comprises a pair of parallel, reinforced anchor members which are respectively secured in recesses in the facing ends of the adjacent concrete pavement slabs; said members having extending between them, tranversely of the pavement, in the gap between the members, a sealing element. The latter comprises a flexible web removably but firrnly held along its longitudinal edges in the anchor members in a manner to seal the gap against entrance of water and other material even during relative movement of the pavement slabs to which the anchor members are attached.

SHORT DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary plan view of the sealing device of the inventioninstalled in a bridge pavement;

FIG. 2 is an enlarged, fragmentary, sectional view on line 22 of FIG. 1',

FIG. 3 is a partially exploded sectional view on line 33 of FIG. 2 showing a joint between two lengths of the sealing device;

FIG. 4 is a further enlarged, fragmentary, sectional view illustrating a modified form of flexible sealing element or web;

FIG. 5 is an enlarged, fragmentary, sectional view, similar to FIG. 4, omitting the sealing element and illustrating the configuration of the anchor members for the sealing element before insertion of the flexible sealing element;

FIG. 6 is an enlarged, fragmentary, sectional view illustrating a possible modification of the anchor members used in the present invention; and

- FIGS. 7 11, inclusive, are enlarged, fragmentary, sectional views, similar to FIG. 4, illustrating other modified forms of sealing elements or webs and means for securing them in place.

DESCRIPTION OF A PREFERRED EMBODIMENT In the joint shown in FIGS. 1 and 2 the numerals l1 refer to adjacent and confronting concrete slabs in a bridge pavement, the slabs being separated at their abutting ends by an opening or gap 12. At the end of each of the slabs 11 there is provided a tranversely extending, shelf-like, recessed portion 13 in which there is received an elongated anchor member 15. The anchor members 15 on the adjacent slabs are spaced apart, the outer edge faces 16 thereof preferably extending only to the edges of the respective slabs 1 l, and are joined in fluid-tight relation by an intervening flexible web member 17 in a manner hereinafter described.

The elongated anchor members 15 are, as shown,

substantially rectangular-in cross-section and preferably of greater width than height. The top 19 and bottom 21 of each of the members 15 are preferably serrated. Extending longitudinally through each of the members 15, preferably between a horizontal plane passing through the middle of the member and the bottom 21 thereof, is a relatively thin, laterally elongated passage 23. Each of the members 15 is also provided with a pair of longitudinally extending bores 25, these being conveniently located, respectively, adjacent the upper corners of the member. The bores 15 are preferably parallel with each other and with the sides and top of the anchor members.

In the abutting edge faces 16 of the members 15 there are provided matching, longitudinally extending channels 27, the inner portions of which are sagittal in cross-section, which are adapted to removably receive and hold the similarly shaped edges 29 of the generally V-shaped-flexible web member 17. When installed, as

shown in FIG. 2, the openings to channels 27 are narrow and the edges thereof fit tightly against the web members at the bases of the enlarged web edges 29 to ensure sealing between the anchor members and-the web member and to hold the web members securely in place.

FIG. 2 illustrates in detail the way in which a novel gap-sealing device according to the present invention is mounted on and between abutting pavement slabs 11. After insertion of the enlarged edges of the sealing member 17 in the facing channels 27, the anchor members 15 are secured in the recessed portions 13 of the concrete slabs with a suitable adhesive bedding compound applied between both the serrated bottoms 21 and the concealed side faces of the members and the contiguous areas of the recessed portions. At spaced intervals along the length of each of the members 15, vertical holes 31 are provided through the member, such holes extending downwardly to an elongated metal reinforcing plate 33 that has substantially the same cross-section as the passage 23 and extends through the passage. Smaller holes 35 and 36, preferably concentric with the holes 31, are provided, respectively, through the plate 33 and the portion of the member below the plate, to receive threaded studs 37. The studs are fixed in the slab 1 l at their lower ends by suitable means and extend upwardly through the holes 35 and 36 into the larger holes 31. By the use of nuts 39 and washers 41, the members 15 can be rigidly but removably anchored to the slab 11. After the nuts 39 are tightened, the holes 31 may be filled with a suitable filler 43, for example an epoxy-modified rubber, a polyurethane resin, or a neoprene or other elastomer composition. Alternatively, caps of rubber or other elastomer may be used over the nuts 39.

The anchor members 15 can be made of any plastic or elastomeric material but are preferably formed of neoprene of at least 70 75 durometer hardness to impart high resistance to abrasion and wear. They may be molded but are preferably extruded, in relatively long lengths, with the passages 23, bores 25, and channels 27 formed in the extrusion process. In many cases, the extruded lengths of the members 15 may be long enough to extend the entire width of the pavement.

Where use of a single length of anchor member is not feasible, a joint such as indicated at A in FIG. 1 may be used. FIG. 3 illustrates the way such a joint may be formed. Metal dowels 45 are inserted in the facing end of the bores 25 of the abutting members 15 to hold the latter in alignment and facilitate insertion of the reinforcing metal plate 33 into the passages 23 thereby to bridge the joint. Thus, the joint between the ends of abutting members 15 is firm and secure. If desired, a suitable adhesive may be applied between the contacting ends of the abutting members 15 to seal the joint. Alternatively, the abutting ends may be provided with tongue and groove or mortised joints or be placed in compression. If desired, the bores 25 need not be provided throughout the entire length of each member 15. Instead, shorter bores may be drilled or molded in the ends of sections of the members to receive aligning dowels in forming end joints. v

The flexible sealing web 17, some times referred to as a rolling gland, is also preferably extruded in relatively long lengths. Other flexible elastomeric or resinous materials, such as natural and synthetic rubber, silicones, polytetrafluoroethylene and ethylene-propylene terpolymers can be used but a low-crystallization neoprene is most satisfactory in many cases. In some cases still other materials may be employed, even thin, flexible metal being satisfactory in some installations of certain types. The thickness and stiffness of the webs 17 may be varied as desired to make the webs suitable for a particular installation. Generally, the width of the web when stretched laterally is at least twice the width of the gap 12 in the pavement joint. Wider webs can be used and, in some cases, narrower ones. However, in

I installations where the joint is to carry trafiic it is important that the width of the sealing element or web be such that, even when the gap 12 between the abutting pavement slabs is at a minimum, for example because of thermal expansion of the slabs, the web'will not protrude from the gap.

As pointed out above, the top and bottom surfaces of the anchor membors 15 are preferably provided with serrations. The serrations on the top provide a good gripping surface for the tires of vehicles and thus tend to minimize slipping or skidding. The serrations on the bottom serve to distribute and hold the adhesive bedding compound employed to secure and seal the anchor members 15 in place in the recesses 13 of the slabs 11. Although in the accompanying drawings the protruding serrations are shown evenly spaced and with flat outer ends, it will be understood that, if desired, they may take other forms and be differently spaced. Compositions suitable for securing the anchor members in the recesses and, when necessary, for splicing lengths of the anchor members are well known.

In assemblying the sealing device illustrated in FIGS. 1 3, the anchor members 15 of the pair required for the installation are laid down in parallel relation with the channels 17 therein facing. As shown best in FIG. 5, a longitudinal slit 47 is formed in the lower portion of each channel 27 so that there are lips or flaps 49 provided along the lower edges of the edge faces 16 of the members 15. Thus, the sagittal edges 29 of the web or gland 17 may be easily inserted in the facing channels by bending back the lips 29. When, however, the anchor members 15 are bolted in place in the recessed portions 13 of the pavement slabs, the lips 49 are forced against the web at the bases of the enlarged edges locking them in the channels and thus firmly securing the web. As will be seen in FIGS. 7 to 9, the angle of the slit is not critical.

A modified construction for locking the gland in place is shown in FIG. 6. In this modification a firm gripping of the edges of the web or sealing member is achieved by providing the channeled face of each of the members 15 with a thickened lower edge which diminishes in thickness inwardly from the face 16' to form a beveled portion 51. When the anchor members are bolted in place as in FIG. 2, the bottoms thereof are flattened and the edges of the web are clamped and sealed firmly even when the openings of the channels 27' are somewhat oversize to permit easy assembly. The angle of the beveled portions 51 and the extra thickness of the edges of the members 15' may vary as required to obtain the desired amount of compression on the edges of the sealing members used therewith. If desired, the channels 7 may also be provided with a slit 47' like the slit 47 in FIG. 5 although this is not necessary.

In FIG. 4 the structure is the same as above-described except that the V-shaped web 17 is replaced by a web 17 that is of greater width than the web 17 and presents in cross-section a multiple V-formation. The web 17' is also provided with side edges 29' that are sagittal in cross-section and fit closely in the channels 27 of the members 15. The greater width of the web 17' permits use of this modified gap-sealing device in joints having wider pavement gaps and permits a greater relative movement between the ends of the abutting pavement slabs without, however, substantially increased stress in the web. In this modified form of the invention, as well as in the form shown in FIG. 2, itwill be seen that the flexible web members provide good sealing with the cooperating anchor members because the edges of the longitudinal channels 27 fit closely against the web member secured therein. The web 17 like the web 17, may vary as desired in width, thickness, and stiffness. As with the web 17, however, it is important in the installations where the joint is to carry traffic that the web 17 does not protrude from between the anchor members when the gap 12 is at a minimum.

Obviously, still other suitable web configurations can be used without departing from the spirit of the present invention. Some of the possible configurations of the flexible web sealing members are illustrated in FIGS. 7 11. In the first three of these figures the anchor members are constructed identically except for the shape of the inner portions of the channels in the edge faces 16. In FIG. 7 the side edges 59 of the web 57 and the inner portions of the channels 61 are semi-circular in crosssection. In FIG. 8 the web or gland side edges 59a and the inner portions of the channels 61a are rounded and somewhat oval in cross-section; and in FIG. 9 the respective edges 59b and channel portion 61b are rectan- FIG. 6. It is desirable, however, to have the enlarged edges of the webs fit rather closely in the channels with which they are used. In this connection it may be noted that, while not necessary, suitable adhesive can be used to hold the sealing members in the channels and seal the formed joints even when the channel forms illusat the joints. In fact, there is nothing critical in the dimensions of the anchor members and they may be changed in size and shape as desired or convenient. Further, it will be evident, there is nothing critical in the spacing of the holes provided in the anchor members for bolting them down. Such holes are preferably cut or bored in the members after extrusion thereof and can be located with any desired intervals between them. In fact, bolting may even be provided for at the abutting ends of sections of the anchor members (such as shown at A in FIG. 1) by cutting matching hemicircular notches (not shown) in the members at such ends. Although the matching holes in the reinforcare shaped to fit the web edges 69 and 79 and the inner portions thereof are directed downwardly at an angle to the horizontal. FIGS. 10 and 1 1 also illustrate certain other possible modifications, specifically the omission of the slits communicating with the channels and making the side edges of a sealing web hollow instead of solid. These constructions are in some cases desirable.

Assembly of the modified forms of sealing members and anchor members shown in FIGS. 4 9 may be carried out in a manner similar to that described in connection with the forms shown in FIGS. 1 3. However, when the slits opening from inner portions of the edge channels are omitted, as illustrated in FIGS. 10 and 11, a different assembly procedure is preferred since the enlarged edges of the sealing member do not readily pass through the openings of the channels. The webs may be easily inserted by sliding the enlarged edge portions into the channels lengthwise. This is facilitated by the use of a lubricating adhesive composition applied to the web edges and/or the channels. The use of such an adhesive, a number of which are commercially available, is in many cases desirable as it not only holds the sealing members in place but also seals the joints between such members and the associated anchor members.

It will be understood that the invention is not to be considered as limited to the particular designs of webs or sealing members and of anchor members illustrated and described herein. Other equivalent designs will be apparent to those skilled in the art. Further, the types of webs and anchor members shown together are not critical. Thus, for example, any of the web edge configurations can be used, if desired, with anchor members in which no slits are provided in the channels of the anchor members, and web edge configurations like those shown in FIGS. 10 and 11 can be used with anchor members formed with slits in the inner portions of the edge channels and/or a thickened edge as shown in ing plates 33 may be drilled after the plates are installed in the anchor members, it is preferred to punch or drill such holes prior to such installation.

Installation of the present novel gap-sealing devices is simple and inexpensive. This is due not'only to the novel construction, but also to the fact that in many cases a continuous length of the device can be used and the need of splicing is thus eliminated. When splicing of the anchor members is required, mitered joints may be used instead of butt joints, if desired. In many cases, sealing of the contiguous ends of the anchor members is unnecessary but, as explained above, they can be sealed by adhesive, if desired. Expensive is reduced and installation facilitated by having the anchor members alike so that no distinct right-hand and left-hand elements are necessary. Consequently, when in position the two facing anchor members are mirror images of each other. Assembly of the anchor members and webs or sealing members to form the joint seals of the pres-' ent invention can be carried out either before delivery to the point of installation or at such point. In the latter case it will generally be more convenient to employ anchor members having a slit in the inner portion of the edge channels since the flap thus formedmakes it possible to insert the enlarged edges of the sealing members in the channels without special holding equipment.

From the foregoing description it will be apparent that the gap-sealing devices of the present invention are highly efficient. Not only is no substantial force applied angle with respect to the other since, because of its shape and flexibility, the web member adjusts for such angle.

The novel structure of the invention makes possible easy installation even when the gap between adjacent pavement slabs varies in size during the course of installation. Installation of joint-sealing devices of other types under such a condition is very difficult, if not impossible. In fact, in some installations long waiting periods may be required to obtain the necessary conditions. In the devices of the present invention, the low stress required to stretch or compress the flexible web or sealing members and the rigidity of the anchor members, even at end joints therein, because of the reinforcing metal plates and the longitudinal dowels at such joints, make it possible to continue installation during expansion or contraction of the pavement slabs.

As explained above, it is preferred to hold the anchor members in place by both the use of adhesive and bolting through the longitudinally extending, reinforcing metal plates. Consequently, buckling cannot occur and, in use, the installation will be substantially noiseless as the reinforcing metal members and securing nuts are situated within the anchor members where they are not contacted by vehicles or other parts of the roadway.

In addition to having the advantages of being substantially noiseless and non-buckling, the gap-sealing devices of the present invention are resistant to wear. In this connection, it should be noted that the design is such that for traffic use the flexible web members do not protrude above the anchor members and hence are not subjected to wear. The sealing of the joint gaps is excellent since, because of the adhesive bedding compound used in securing the anchor members in the recesses 13, there is no leakage around them and the snug fit and/or adhesive sealing of the web members, which are themselves impermeable, in the channels of the anchor members precludes passage of water into the gap around the webs.

It will be understood that the scope of the present invention is not limited to the specific construction described and illustrated in this application since numerous modifications can be made therein without departing from the spirit of the invention. Consequently, the invention should be construed as broadly as permitted by the appended claims. It will also be understood that the novel sealing device of the present invention is capable of wide use and is not limited to use in roadways and the like.

We claim:

1. A gap-sealing device particularly suitable for bridges, over-passes, ramps, and the like which comprises: a pair of longitudinally extending, laterally spaced anchor members provided with longitudinally spaced means for fastening them to supports, each of said members being substantially rectangular in crosssection, formed of relatively hard elastomeric material, and provided with a longitudinal passage therethrough, said members having in their facing edges channels extending longitudinally of said members, each of said channels comprising a narrow opening and an enlarged inner portion and having a slit in the wall of said enlarged inner portion thereof whereby to form a hinged lip at the lower edge'of said anchor member adjacent said channel; a reinforcing plate extending through said passage and having substantially the same cross-section as said passage; and an elongated, flexible, impermeable web of elastomeric material extending longitudinally between and joining said anchor members, said web having enlarged side edge portions removably engaged directly in said channels; and said web being clamped in said channels.

2. A gap-sealing device as defined in claim 1 in which said anchor members are of neoprene and said web is of low crystallization neoprene.

3. A gap-sealing device as defined in claim 1 in which said web is in part V-shaped in cross-section.

4. A gapsealing device as defined in claim 1 in which said web includes a plurality of integral V-shaped sections.

5. A gap-sealing device as defined in claim 1 in which said anchor members are serrated on at least one surface thereof.

6. A gap-sealing device as defined in claim 5 in which said anchor members are serrated on both the top and bottom.

7. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are hollow.

8. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are sagittal in cross-section.

9. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are curved in cross-section.

10. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are rectangular in cross-section.

11. A gap-sealing device as defined in claim 1 in which said longitudinal passages lie below the horizontal center lines of the anchor members.

12. A gap-sealing device as defined in claim 11 in which said reinforcing plates are of metal.

13. A gap-sealing device as defined in claim 1 in which said anchor members are provided with bores extending longitudinally thereof for reception of aligning means.

14. A gap-sealing device as defined in claim 1 in which the lower facing edges of said anchor members are thickened.

15. A gap-sealing device as defined in claim 14 in which said anchor members are of neoprene, are serrated on at least one surface thereof, and are provided with longitudinally extending bores for reception of aligning means; in which said web is of low crystalliza-- tion neoprene and is in part V-shaped in cross-section; and in which the enlarged edge portions of said web are sagittal in cross-section.

16. A gap-sealing device as defined in claim 1 in which said anchor members are of neoprene, are serrated on at least one surface thereof, and are provided sagittal in cross-section.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 9 Dated November 26, 1974 Inventor(s) Thomas C. Bowman et a1 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 25, before "lips" hinged has been inserted.

Column 4, line 52,"7' has been changed to 27' Column 6, line 41, 'Ex ensive" has been changed to Expense.

Signed and sealed this 1st day of April 1-575.

(S EAL) Attest:

C IKARSHALL DACN RUTH C. MASON Commissioner of Patents attesting Officer and Trademarks FORM PC4050 (IO-69) USCOMM-DC OO376-P69 LLS. GOVERNMENT PRINTING OFFICE 2 ll. 0-36-33. 

1. A gap-sealing device particularly suitable for bridges, overpasses, ramps, and the like which comprises: a pair of longitudinally extending, laterally spaced anchor members provided with longitudinally spaced means for fastening them to supports, each of said members being substantially rectangular in cross-section, formed of relatively hard elastomeric material, and provided with a longitudinal passage therethrough, said members having in their facing edges channels extending longitudinally of said members, each of said channels comprising a narrow opening and an enlarged inner portion and having a slit in the wall of said enlarged inner portion thereof whereby to form a hinged lip at the lower edge of said anchor member adjacent said channel; a reinforcing plate extending through said passage and having substantially the same cross-section as said passage; and an elongated, flexible, impermeable web of elastomeric material extending longitudinally between and joining said anchor members, said web having enlarged side edge portions removably engaged directly in said channels; and said web being clamped in said channels.
 2. A gap-sealing device as defined in claim 1 in which said anchor members are of neoprene and said web is of low crystallization neoprene.
 3. A gap-sealing device as defined in claim 1 in which said web is in part V-shaped in cross-section.
 4. A gap-sealing device as defined in claim 1 in which said web includes a plurality of integral V-shaped sections.
 5. A gap-sealing device as defined in claim 1 in which said anchor members are serrated on at least one surface thereof.
 6. A gap-sealing device as defined in claim 5 in which said anchor members are serrated on both the top and bottom.
 7. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are hollow.
 8. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are sagittal in cross-section.
 9. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are curved in cross-section.
 10. A gap-sealing device as defined in claim 1 in which the enlarged edge portions of said web are rectangular in cross-section.
 11. A gap-sealing device as defined in claim 1 in which said longitudinal passages lie below the horizontal center lines of the anchor members.
 12. A gap-sealing device as defined in claim 11 in which said reinforcing plates are of metal.
 13. A gap-sealing device as defined in claim 1 in which said anchor members are provided with bores extending longitudinally thereof for reception of aligning means.
 14. A gap-sealing device as defined in claim 1 in which the lower facing edges of said anchor members are thickened.
 15. A gap-sealing device as defined in claim 14 in which said anchor members are of neoprene, are serrated on at least one surface thereof, and are provided with longitudinally extending bores for reception of aligning means; in which said web is of low crystallization neoprene and is in part V-shaped in cross-section; and in which the enlarged edge portions of said web are sagittal in cross-section.
 16. A gap-sealing device as defined in claim 1 in which said anchor members are of neoprene, are serrated on at least one surface thereof, and are provided with longitudinally extending bores for reception of aligning means; in which said web is of low Crystallization neoprene and is in part V-shaped in cross-section; and in which the enlarged edge portions of said web are sagittal in cross-section. 